Anatomical and physiological evidence indicates that discrete regions of the amygdala, specifically the central nucleus and the bed nucleus of the stria terminalis, are responsible for activating cardiovascular, respiratory, gastric, and nociceptive responses that occur during stressful or aversive conditions. These responses are mediated through descending pathways from the amygdala to the brainstem and spinal cord. It is hypothesized that these pathways are organized according to both their neuropeptide content and their anatomical relationship to central catecholamine-containing neurons and preganglionic autonomic neurons. Studies are proposed that will examine amygdalar axon terminal topography within sympatho-activating, catecholamine containing, and respiratory regions of the brainstem and spinal cord. Amygdalar axonal terminal zones to be studied include the midbrain central gray, locus coeruleus, parabrachial nucleus, A5 catecholaminergic neurons, dorsal vagal complex, ventrolateral medulla and cervical spinal cord. Also, the anatomic relationship of amygdalar terminals to catecholaminergic neurons and cells projecting to preganglionic sympathetic regions of the spinal cord will be examined. A new highly sensitive anterograde tracer, Phaseolis vulgaris leucoagglutinin lectin, will be combined with catecholamine immunocytochemical and fluorescent dye retrograde tracing methods to accomplish these experiments. Experiments are also proposed to identify the neuropeptide content and intra-amygdalar organization of neurons which innervate the above regions of the brainstem and spinal cord. A modification of the combined fluorescent retrograde tracing and immunocytochemical technique will be employed to perform these experiments. The data will be analyzed using both quantitative and qualitative methods. The amygdala, its putative transmitters and interconnected brainstem/spinal regions participate in the development and expression of cardiovascular disease (e.g., hypertension and cardiac arrhythmias) and gastric disorders (e.g., stress-induced gastric ulcers). Therefore, the data collected by this proposal should aid in the clinical treatment and further basic scientific study of central autonomic-related diseases.